The drive support apparatus provides a drive support for a driver of a vehicle, with a sophistication of determining whether the drive support is really necessary in a certain situation, i.e., determining whether providing a drive support to a driver really supports the driver or actually bothers him/her.
For example, according to a patent document, Japanese Patent Laid-Open No. 2013-134567 (patent document 1), an in-vehicle camera is used to determine whether a currently-traveled road that is traveled by a subject vehicle is a priority road or a non-priority road, i.e., whether one vehicle on a certain road has a priority of crossing/entering an intersection against the other vehicle that is on an intersecting road, for example. Then, when it is determined that the subject vehicle is on a priority road, the existence of the other vehicle is not reported/notified to a driver of the one vehicle.
When a captured image from the in-vehicle camera is analyzed for a determination of whether or not the subject vehicle is traveling on a priority road, the image analysis has to be “sequentially” performed, or for image by image basis. That means, an image analyzer has to have a high performance Central Processing Unit (CPU) or the like, for handling a high processing load.
Further, the patent document 1 discloses that the determination of whether the subject vehicle is traveling on a priority road is made based on information obtained via a vehicle-to-vehicle communication, or is made based on a vehicle behavior of stopping at/around an intersection. However, a vehicle can obtain information via a vehicle-to-vehicle communication only in a limited area. Further, a stop behavior of a vehicle can tell whether the subject vehicle is traveling on a priority road only in a limited situation.
A travel locus of the subject vehicle may be map-matched to a road shape of a road map, which may be known as a so-called “map matching”. Therefore, the map matching technique may be utilized for determining whether the subject vehicle is traveling on a priority road or on a non-priority road. Map matching does not put a very high processing load on a processor, and is applicable to many situations for the determination of a priority road, i.e., for determining whether the subject vehicle is traveling on a priority road.
However, road map information used in the map matching represents an intersection as an intersection node, e.g., as a “point”, thereby causing a mis-match, e.g., mis-determination in which a vehicle actually traveling “in” an intersection area is determined as traveling on one of the two links (i.e., two roads) that are connected to a certain intersection node.
Further, a situation may be more complicated at or around an intersection, which may have a few (e.g., two, three, four or more) connected roads, among which a vehicle has to be matched/mapped to only one of the connected roads (i.e., to only one of plural candidate roads). Thus, when the subject vehicle is traveling in an intersection area or around (i.e., at a proximity of) an intersection, the subject vehicle approaching that intersection in reality for a left/right may be falsely determined by the map matching as having already turned at that intersection and traveling on the rightward-extending road or on the leftward-extending road therefrom. As a result, the currently-traveled road on which the subject vehicle is traveling may also be falsely determined as a priority road or as a non-priority road. Based on such a false determination, the drive support for the driver (i.e., for the drive operation) may also be falsely/wrongly provided, i.e., may be provided in an in-accurate/non-suitable manner. That is, when a priority/non-priority road determination is wrong, whether to suppress the drive support or not is determined in an in-accurate manner.